*6.2.1 Phenotypic assays*

WHO bioassays are most commonly used diagnostic assay for detecting insecticide resistance in *Culex* phenotypically which is proved by extensive experimental

studies such as to detect the knockdown resistance in *Cx. quinquefasciatus* in Sri Lanka [80]; as the diagnostic assay in *Cx. pipiens* against organochlorine, pyrethroid, organophosphate and carbamate insecticides. Larval bioassay by microplate method in the *Cx. pipens* larvae has also been carried out to study the knockdown and metabolic resistance in filariasis endemic areas of Egypt [81]. In India, following the WHO diagnostic methods for phenotypic detections, susceptibility studies have been carried out against DDT and Deltamethrin in *Cx. quinquefasciatus* from northeastern India to study the target sited resistance in this vector [82]. Some other studies have also been carried out using WHO bioassays for detecting the insecticide resistance such as metabolic resistance in *Cx. pipiens pallens* in China [83]; target sited mutations of genes G119S ace-1 and L1014F in *Cx. pipiens* complex and their hybrids in Morocco [84].

### *6.2.2 Genotypic assays*

PCR based methods such as amplification of specific gene targets by PCR followed by sequencing of the amplified product can be used to detect specific mutations associated with resistance. For example, L1014F mutation on the VGSC domain IIS6 had been reported in *Cx. quinquefasciatus* in Sri Lanka associated with resistance to insecticides [85]. Various resistance genes have also been discovered through transcriptome profile by whole-transcriptome microarrays in *Culex* species. With the help of pyrosequencing, the mutations and metabolic insecticide resistance due to deltamethrin in *Cx. quinquefasciatus* from Zanzibar was determined [86]. These assays provided evidence for insecticide resistance caused due to target site mutations and metabolic alterations at the genetic level [87].

#### *6.2.3 Proteomics assays*

A global protein profile among insecticide resistance strains and susceptible strains of *Culex* may be obtained through proteomics. The alterations at the proteomics level can be determined by quantification of certain tags using liquid chromatography/tandem mass spectrometric analysis. The protein profiles have also been detected using isobaric tag for relative and absolute quantitation (iTRAQ ) data analysis method which has confirmed the susceptibility status of strains of *Culex* in studies [88]. Such studies assure that proteomics can be considered as promising tools for studying insecticide resistance in mosquito populations.

### **6.3 Detection of insecticide resistance in the vector of** *Leishmania***: Sandfly**

#### *6.3.1 Phenotypic assays*

The WHO bioassays detected the knockdown resistance type mutations and certain metabolic enzyme resistances due to exposure of DDT, malathion, deltamethrin and propoxur in *Phlebotomus argentipes* [89]. Another study detected the resistance in *Paralongicollum sergenti* and *P. papatasi* on exposure to DDT and lambdacyhalothrin in Morocco [90]. The WHO and CDC bottle bioassays have also been conducted to study the diagnostic time and dose in *P. papatasi* to study insecticide resistance for pyrethroids, organophosphates, carbamates and DDT [91].

#### *6.3.2 Genotypic assays*

The detection of molecular alterations such as the mutations in *VGSC* gene have been detected in sandflies [92]. The pyrethroid resistance mutations (kdr) were

*Insecticide Resistance in Vectors of Medically Important Parasitic Infections DOI: http://dx.doi.org/10.5772/intechopen.100583*

also studied in the sandfly vector population worldwide with PCR as the major tool for detection [93]. Target site resistance of voltage gated sodium channel gene (kdr mutations) at position L1014F/S in *Phlebotomus papatasi* has also been determined through PCR [91].
